/* Copyright (C) 2013-2021 TU Dortmund
 * This file is part of AutomataLib, http://www.automatalib.net/.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.automatalib.commons.util.settings;

import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Properties;
import java.util.ServiceLoader;

import com.google.common.collect.Iterators;

public interface SettingsSource {

    static <S extends SettingsSource> Properties readSettings(Class<S> clazz) {
        Properties p = new Properties();
        readSettings(clazz, p);
        return p;
    }

    static <S extends SettingsSource> void readSettings(Class<S> clazz, Properties p) {
        ServiceLoader<S> loader = ServiceLoader.load(clazz);
        List<S> sources = new ArrayList<>();
        Iterators.addAll(sources, loader.iterator());
        sources.sort(Comparator.comparingInt(SettingsSource::getPriority));

        for (S source : sources) {
            source.loadSettings(p);
        }
    }

    void loadSettings(Properties props);

    default int getPriority() {
        return 0;
    }
}
